This invention relates to a fuel system for a vehicle internal combustion engine and of the kind in which an operator controlled electrical signal is utilised as an input signal to the fuel system to determine the rate of fuel supply by the fuel system to the associated engine.
In such a fuel system for a compression ignition engine there may be provided a high pressure fuel pump having a quantity control member which may for example be a rack bar or an angularly adjustable throttle member, the position of which is determined by an electromagnetic actuator. The supply of electrical power to the actuator is controlled by an electronic control system in response to said signal. The quantity control member may also be in the form of an electromagnetically operable valve controlled by the control system. In the case of a spark ignition engine the usual butterfly valve may be positioned by means of an electromagnetic actuator with the supply of power to the actuator being controlled by said signal.
In the use of the vehicle the driver becomes used to the performance of the vehicle and the response of the vehicle to changes in the position of the throttle pedal. Clearly if an additional load is imposed on the vehicle such for example as an additional passenger or some additional cargo, the driver will expect the performance of the vehicle to be diminished. However, in the normal use of the vehicle additional loads such as a heavy electrical load or an air conditioning compressor may be applied to the engine unexpectedly and the apparent performance of the vehicle impaired when the load is applied or enhanced when the load is removed. Such an event will require corrective action on the part of the driver to maintain the desired vehicle speed or rate of acceleration.